In the case of when 1-alkene, in particular, ethylene is copolymerized in conjunction with an alkyl acrylate comonomer, a polymer that has different physical properties which are not capable of being obtained in a simple polyethylene may be formed. Examples of the physical properties include attachment strength, low temperature toughness and the like, and they may be largely improved according to an increase in content of the alkyl acrylate comonomer(s). Accordingly, the development of the copolymer that includes 1-alkene and another comonomer mixed with each other has been watched with the keen interest.
In a general known art, ethylene and an alkyl acrylate copolymer are obtained from a high temperature and high pressure reaction. Accordingly, there is disclosed a production method in which ethylene and the acrylate monomer are added simultaneously under a severe condition of 1000 atm or more and 100° C. or more by using a tube-type reactor or autoclave reactor. The polymer that is obtained under the above condition is a copolymer that includes 3 to 35% of acrylate monomer that is a polar monomer on the basis of ethylene.
However, in order to realize the high temperature and high pressure condition, additional devices such as a first compressor, a second compressor, a special reactor and the like are required in order to ensure safety of a worker. In addition, because of the severe process condition, in order to change a composition change of the copolymer in a desired direction, there are many limits.
In addition, the ethylene copolymer that is produced by using a known method includes a little polar group. That is, since the content of the polar monomer is not high, the crystallinity of polyethylene is present in the copolymer, thus there is a limit in use of the copolymer as an optical material such as a transparent film and the like.
In addition, in respects to the polymer that is obtained by using the high temperature and high pressure method in a known tube-type reactor or autoclave, products that do not largely affect the transparency have been mainly developed.
Therefore, there remains a need to develop a method for producing a novel polar copolymer, in which a copolymer having no crystallinity is capable of being produced because the content of the polar comonomer is high without the severe polymerization condition of high temperature and high pressure.